Mutual Coupling Analysis of a Dual Circularly Polarised Contrawound Quadrifilar Helix Antenna (cqha) in Land Mobile Satellite (lms) Mimo Systems

Analysis of the mutual coupling and its effect on the CQHA performance in LMS MIMO system are investigated and presented in this paper. Due to the complexity of the CQHA structure, the mutual coupling effects were mainly studied using electromagnetic simulation. The effect of the separation spacing between inner and outer QHA on the mutual coupling was investigated by comparing the element isolation of CQHAs with varying outer QHA radius and fixed inner QHA radius. It can be concluded that a minimum separation of 0.1λ is required for the isolation to be better than 15dB. The distortion of the co-polar and cross-polar radiation patterns of the CQHA due to the mutual coupling are also studied in this paper. Finally, the effect of the mutual coupling on the mean effective gain and polarisation correlation of CQHAs with varying separation spacing between inner and outer QHA were examined and its results showed that the MEG values are very much affected by mutual coupling while the polarisation and angular correlation are largely unaffected.